1. Field of the Invention
The field of the invention is the separation, condensation, and storage of liquid sulphur from a Claus plant used to remove sulphur-containing compounds from industrial process gases, preferably coke oven gases.
2. Description of the Related Art
The production of industrial gases frequently yields a sulphur-containing gas which must be freed from sulphur compounds. Treatment is typically carried out in a gas scrubber in which the sulphur-containing gas is brought into contact with an absorption liquid which is freed again from these sulphur compounds in a subsequent desorption step such that these can be passed to a Claus process. Typical industrial gases which must be freed from sulphur compounds are coke oven gas, natural gas or refinery gases.
The Claus process allows that the sulphur compounds are converted to elemental sulphur, this conversion being started by burning the sulphur compounds with the aid of an oxygen-containing gas. This gives elemental sulphur, whereas carbon and hydrogen react to form carbon dioxide and water. The combustion gas is fed to a waste heat boiler in which the sulphur condenses to a liquid. The liquid sulphur can then be passed to a further process step or disposal. The condensed and desulphurised gas from the waste heat boiler is fed to a Claus reactor where the residual sulphur compounds are passed to a combustion stage, sulphur dioxide being obtained which, by reacting with residual hydrogen sulphide in the presence of a catalyst, is converted to elemental sulphur. The reaction step for the conversion of sulphur dioxide with hydrogen sulphide can be provided several times to achieve the maximum degree of desulphurisation.
A typical embodiment of the Claus process is disclosed in EP 1527013 B1. This teaching lays claim to a process for the separation of hydrogen sulphide from coke oven gas, in which the hydrogen sulphide is removed from the coke oven gas by gas scrubbing using an absorption liquid, the laden absorption liquid is regenerated and the laden absorption liquid and the hydrogen sulphide obtained in concentrated form are fed to the Claus plant, the hydrogen sulphide reacting with atmospheric oxygen in a Claus boiler of the Claus plant giving elemental sulphur, and the process gas leaving the Claus boiler being cooled down in a waste heat boiler to a temperature required for the condensation of the sulphur, then, after separation of the sulphur, being heated and fed to a reaction furnace of the Claus plant. In said reactor the sulphur compounds react in the presence of a catalyst to give elemental sulphur, and the process gas leaving the reaction furnace is cooled down to a temperature required for the condensation of the sulphur, and the condensed sulphur is separated, the Claus plant according to the invention being operated by one single reaction furnace only, the operating temperature of which being adjusted to less than 250° C., and the process gas leaving the reaction furnace is recycled after separation of the condensed sulphur to the coke oven gas to be treated together with residual hydrogen sulphide not converted in the reaction furnace prior to gas scrubbing. The teaching does not refer to any storage and further processing of the sulphur obtained in the process.
Normally, this sulphur is separated in liquid form and stored after solidification. The solid sulphur can be further used for versatile purposes, for example, as starting material for chemical syntheses or for the production of sulphuric acid. In the condensation of the sulphur, part of the sulphur is obtained in liquid form, whereas the remainder is still contained in the form of fine droplets in the condensed gas. To facilitate the formation of sulphur droplets of a size suitable for separation, the condensed gas can be fed to a siphon-type device where an almost complete separation of sulphur is achieved.
DE 2756992 C2 gives an example of a device which facilitates complete condensation of the sulphur contained in a sulphur-containing combustion gas. The said teaching discloses a device for the separation of sulphur droplets from a gas stream, preferably from a reaction gas stream of a Claus catalyst, this device consisting of a housing, a tube bundle arranged in the housing between the tubesheets, nozzles on the housing for the supply and discharge of a coolant flowing around the tube bundle and one gas stream inlet and outlet nozzle each on the housing on the inflow and outflow side of the tube bundle, with a separating unit, passed by the gas stream, being arranged in the housing between the tubesheet on the gas outlet side of the tube bundle and the gas outlet nozzle as well as outlets on the housing bottom on the inflow and outflow side of the separating unit for the sulphur separated upstream or in and downstream of the separating unit according to the invention. In an embodiment the device includes lines which convey the liquid sulphur from a separating unit to a sulphur collecting tank where they dip-in in a siphon-like manner.
The embodiment mentioned has the disadvantage that the sulphur withdrawn from the discharge nozzle cannot be stored but must be transported onwards in liquid form. In addition, no supply option for liquid sulphur as obtained, for example, in a waste heat boiler of a Claus plant is provided.